If you would like to see plots, just go to the next page. Otherwise, this is a short introduction so this can be understood in a glimpse.
The point of my thesis was to build a magnetic field sensors that uses an optical fibre. This was accomplished by building different types of interferometers, with ferrofluid reacting with magnetic field.
The sensor with a ferrofluid-filled capillary described in this paper has not been previously described in literature, or I couldn’t find any.
When two waves of light meet each other, and their lenghts match, they can add or substract from each other. This is called interference. This act can happen for a whole range of wavelengths. In our case, the light can interfere when it is inside of a capillary.
A cappilary, or “no core fibre” is just a tiny little pipe, made our of glass. It has a small hole inside, and we assume that it’s inside and outside circumference is always of the same size.
A ferrofluid is a fluid, filled with tiny particled that react with magnetic field. That way, we can change the most important property - the angle by which light gets reflected - using magnetic field. In my study, I tested two ferrofluids made by Ferrotec company.
By placing a cappilary in a ferrofluid, we can alter its optical property using magnetic field. That way, and adding that each wavelength refracts at a slightly different angle, we can measure changes made to a wide spectrum of light by a
As the magnetic induction changes, the each wavelengths refracts at slighly different angle